Magnetic dart board



April 28, 1970 G. E. LEMON 3,508,132

MAGNETIC DART BOARD Filed Aug. 21, 1968 2, Sheets-Sheet l INVENTOR. GEORGE E. LEMON AGENT April 8, 1970 G. E. LEMON 3,508,752

MAGNETIC DART BOARD Filed Aug. 21. 1968 2 Sheets-Sheet 2 IN VEN TOR. GEORGE E. LEMON BY AGENT United States Patent US. Cl. 273-102 6 Claims ABSTRACT OF THE DISCLOSURE Disclosed is a dart board for use with darts having magnetic tips. The metal target is mounted for limited movement along the path of travel of the darts. An electromagnet is provided a short distance behind the target and, when the dart approaches the target, a detector mechanism, a light beam and photocell arrangement in the preferred embodiment, is actuated and the detector in turn energizes the electromagnet, thus causing the dart board to be pulled rearwardly. When the target has reached the rear limit of its path of travel, it trips a limit switch de-energizing the electromagnet and permitting the target to return to its normal position.

This invention relates in general to dart boards and more particularly to an improved arrangement for a dart board for use with magnetic tipped darts.

While magnetic tipped darts are safer than conventional pointed tip darts, they are inferior to the conventional darts as they fail to stick to the target unless thrown with extreme accuracy.

It is the primary object of my invention to provide an improved magnetic dart board which readily retains the darts striking the board. It is also an object of my invention to provide a dart board in which the target may be caused to move along the path of travel of the dart when the dart approaches the board, reducing the force of impact between the dart and the board. Another object of my invention is to provide a magnetic dart board in which the holding power between the dart and the board is increased. A further object of my invention is the provision of a magnetic dart board which is of simple, economical construction.

The above and other objects and advantages of my invention will become apparent upon consideration of the following specification and the accompanying drawing wherein there is shown a preferred embodiment of my invention.

In the drawing:

FIGURE 1 is a front elevational view of a dart board constructed in accordance with my invention;

FIGURE 2 is a longitudinal sectional view, taken along the line II-II of FIGURE 1;

FIGURE 3 is a transverse sectional view, taken along the line III-III of FIGURE 1;

FIGURE 4 is a schematic diagram of the actuating circuit employed in the dart board of FIGURE 1; and

FIGURE 5 is an elevational view of a dart used with the board of my invention.

In the drawings, reference numeral designates a metal plate which is provided with markings 11 on one face and which serves as a target for darts. The plate 10 is preferably square and is provided with a hole 12 at each of its four corners. A pin or stud 13 passes through each of the holes 12 and is joined to a rear member 16. Each pin is provided with a pair of compression springs 14, 15, mounted on opposite sides of the target 10 for a purpose to be hereinafter described. An electromagnet 17 is also mounted on the rear plate 16 a short distance behind the target 10 and adjacent the center thereof.

Two opposite edges 18, 19 of the rear plate 16 project forwardly beyond the target 10. Each of the projecting portions 18 and- 19 is provided with a front portion 20, 21, respectively, extending parallel to the main portion of the back plate 16 and supporting one end of a pair of channels 22, 23, respectively, the opposite ends of which are supported by the rear plate 16. One pair of channels 22 support a sliding plate 24 which is provided with a plurality of apertures 25. The other pair of channels 23 carry a slide 27 which is likewise provided with a plurality of apertures 28, the apertures 25 and 28 being located in corresponding positions on the slides 24 and 27. The sliding member 24 carries a plurality of photocell units 26, one unit being mounted behind each of the apertures 25 and the sliding member 27 carries a plurality of lights 29, one light being provided behind each of the apertures 28. The apertures 25 and 28 and, therefore, the photocells 26 and lights 29 are so arranged that the distance between successive pairs of lights and photocells is at least slightly less than the width of the tip of the dart so that at least one light beam is interrupted when a dart approaches the board. The rear plate 16 also mounts a limit switch 30 which is so positioned that it is tripped when the target reaches the rear extent of its travel on the pins 13.

As will be seen from FIGURE 4, the photocells 26 are connected in series. The series of photocells is connected to a relay 31 having a normally open contact 32. When none of the rays of light extending from the lights 29 to the corresponding photocells 26 is interrupted all the photocells 26 are conducting and the relay is energized holding the contact 32 in its open position and keeping the electromagnet 17 in a de-energized state. When a dart approaches the board it passes through at least one of the beams of light and thus causes one or more of the photocells 26 to stop conducting. The relay 31 is now de-energized and the contact 32 closes, energizing the electromagnet 17. The magnet 17 attracts the target 10 rearwardly in the same direction that the dart is moving. As the dart and target are moving in the same direction at the instant the dart contacts the target, the force with which the dart strikes the target is reduced and, therefore, the tendency of the dart to rebound from the target is also reduced. Further, the magnetic field set up in the target by the energized electromagnet 17 increases the attracting force between the target and the dart and, thus, helps to insure that the dart remains on the target. Since the light ray is interrupted only momentarily and thus one of the photocells 26 ceases to conduct for only an instant and begins conducting before the dart has reached the target 10 thus re-energizing the relay 31, I provide a latching arrangement to hold the relay 31 in its de-energized condition even after the photocells 26 are again conducting. Relay 31 is preferably of the kind having a second coil which when energized holds the relay in position. This second coil is energized when the relay becomes de-energized closing the contact 32. The second coil remains energized until the limit switch 30 is opened which occurs when the target 10 reaches the rear limit of its travel. When the limit switch 30 is tripped, the relay 31 returns to its energized position, the contact 32 opens, and the electromagnet 17 is de-energized. The springs 15 which have become compressed as the target 10 moved rearwardly toward the electromagnet 17 are now free to move the target 10 forwardly towards its normal position. The springs 14 serve to restrain the forward movement of the target 10 and in combination with the springs 15 rapidly dampen the oscillations forward and rearward of the target 10 and thus prevent the darts which have adhered to the target from being jiggled oif.

It will be readily apparent that the combination of the target moving in the same direction as the dart and the increased magnetic field of the target result in an improved adherence of the dart to the target. Further, the dampening action of the springs 14 and 15 aid in preventing darts which have adhered to the target from being shaken free therefrom when the target returns to its normal position.

The time interval between the moment a light beam is interrupted by the tip of an incoming dart and the moment of impact of the dart against the target may be varied so that the dart strikes the targets at the most advantageous moment. In the illustrated embodiment this is accomplished by moving the slides 24 and 27 forward or rearward to increase or decrease, respectively, the time interval. While in the drawing the forward movement of the slides 24 and 27 are limited by the front panels 20 and 21, it will be understood that these panels may be cut away in the regions between the channels 22 and 23 to clear the slides 24 and 27, the lamps 29, and the photocells 26. Also, the channels 22 and 23 may be of any desired length permitting the adjustment of the interval between detection and impact to be varied as desired.

It will be understood that my invention is not limited to the embodiment shown and that changes may be made in and to my invention without departing from the spirit thereof. In particular, the means for detecting the approach of the darts is illustrative only and any suitable means may be employed for this purpose. Also, the gist of my invention, a target which is moved by an electromagnet when a projectile approaches the target, may be used with any type of target and need not be specifically limited to dart boards used with magnetic tipped darts.

I claim:

1. A dart board for use with magnetic tipped darts, comprising: a magnetically attractable target; a back member extending parallel to said target and spaced therefrom; means mounting the target to the back member for uniform movement toward and away from the back memher, and having means to bias said target in a normal position spaced forwardly of the back member; an electromagnet means mounted on said backing plate a spaced distance from said target and adjacent the center thereof for causing movement of the target member toward the back member from said normal position; detecting means disposed forwardly of said target for detecting the approach of a dart toward said target; circuit means responsive to said detecting means to energize said electromagnet, said circuit means including means to tie-energize said magnet when said target has reached the rear extent of its travel.

2. Apparatus according to claim 1 further characterized in that said means to energize said electromagnet may be adjusted to vary the length of time said electromagnet is energized.

3. Apparatus according to claim 1 further characterized in that said detecting means includes a plurality of lights and a plurality of photocells arranged to form a detecting zone wherein a dart approaching said target interrupts the beam of light from at least one of said lights to at least one of said photocells.

4. Apparatus according to claim 3 further characterized in that said plurality of photocells are mounted on a sliding member adjacent one edge of said target; and said plurality of lights being mounted on a sliding member adjacent the opposite edges of said target.

5. Apparatus according to claim 3 further including a relay; said plurality of photocells being connected in se ries relationship with one another and said relay, and said relay having a normally open contact in series connection with said electromagnet.

6. Apparatus according to claim 5 further including means holding said electromagnet in an energized state after the termination of the interception of the light beam extending from at least one of said lights to at least one of said photocells, said last mentioned means being operative to return said electromagnet to a de-energized state when said target has reached the rear limit of its travel.

References Cited UNITED STATES PATENTS 2,050,914 8/1936 Anderson 273-102 2,683,037 7/ 1954 Ruczynski et al. 3,203,698 8/1965 Saunders 273102.4 3,229,975 1/ 1966 Tompkins et al. 3,401,937 9/ 1968 Rockwood et al.

FOREIGN PATENTS 10,992 1906 Great Britain.

ANTON O. OECHSLE, Primary Examiner M. R. PAGE, Assistant Examiner U.S. Cl. X.R. 273102.2 

